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Topic: Mounting Scope - who uses a level? (Read 868 times)

I was carefully mounting buddyís scope then realized - why bother? Just adjust til it sits and looks level when you shoulder it. The only important thing is that the level indicator ( you have one right?) matches up with the scope crosshairs.

If I naturally shoulder the stock canted 3 degrees then leave it there just make sure scope is vertical at that point.

Does anyone level their scope to where they naturally shoulder their stock instead trying to get stock perfectly level? Seems like a novel concept.

Won't a 3 degree cant alter the drop relative to the crosshairs? In a zero sidewind environment, I expect my bullets to drop exactly along the vertical crosshairs.

To illustrate the point, mount a scope at 45 degrees to the right and go shooting. On zero it wouldn't matter, but if you needed to hold over at all you're going to send the bullet to the right of the target (assuming you use the lower half of the vertical crosshair to determine where bullet will drop).

There's another issue if you have CDS dials. The vertical drop is calculated assuming a straight drop. But if your scope is canted, you're vertical calculation is actually the hypotenuse of a right triangle, and the actual bullet drop is the long leg. There's some trigonometry involved now, and you could actually calculate it for each shot using the angle of cant. In your 3 degree scenario, the bullet will drop a factor of .99863 of what they CDS dials predict. still trying to figure it how to relate this to real-world results

This isn't taking into account the additional windage introduced because of the 3 degree cant of the pipe relative to the line of sight either. The more offset the line of sight is from the bore, the more introduced windage you'll see.

At most common hunting ranges, it won't matter. But at 1000 yards, it could.

*Ok, I figured it out. Using the 3 degree tilt to to the right and CDS dial scenario, your bullet will hit a factor of .137% low from CDS calculated drop and 5.23% of the calculated drop to the right of the target.

So at 1000 yards, if the round you're shooting is calculated on the dials to drop 100 inches from line of sight, you will actually hit .137 inches lower and 5.23 inches to the right.

Yes scope needs to be vertical at the shot - but stock/action/barrel can be anywhere. Doesnít matter - right???

Practically, it doesn't. But let's say you're shooting a 45-70 at 1000 yards, and need 45 degrees of difference between line of sight and barrel.

If you imagine another triangle (this will be a right triangle) one leg is the scope and the hypotenuse is the barrel. If you rotate the triangle along the scope 10 degrees to the right, the barrel (hypotenuse) rotates as well. As it does so it "swings" out of line with the scope, and is now pointing to the right of the scope's line of sight.

It's not much, but it's there. If you had some data we could calculate actual numbers. We'd need the zero yardage, angle of scope cant, height of scope mounted from barrel, and bullet trajectory/drop at various yardages.

I mount a bipod on the gun and set it down on the groundThen behind the gun use a plumb line as close to the wall as possibleI max out the eyepiece and use a surefire light at the objective lens to project the cross hairs onto the wall..

I then adjust it to match up with the plumb line and tighten up checking often.

Not all crosshairs are level with the scope tube it sits in.

This is just the method I use and it's worked for me. However I'm sure there are better ways.

I mount a bipod on the gun and set it down on the groundThen behind the gun use a plumb line as close to the wall as possibleI max out the eyepiece and use a surefire light at the objective lens to project the cross hairs onto the wall..

I then adjust it to match up with the plumb line and tighten up checking often.

Not all crosshairs are level with the scope tube it sits in.

This is just the method I use and it's worked for me. However I'm sure there are better ways.

Skillet illustrated it pretty well, but it absolutely does matter that your crosshairs are perfectly vertical to your barrel. Your scope and barrel are not on the same plane, so if there is any cant, adjusting a vertical turret accounts for less vertical than it should, and adjusts left or right depending on your cant. It will make you second guess your wind calls.

If it's a brush gun, in all reality eyeballing it is fine. For any 'long range' shooting you need to be vertical.